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iOS

Posted by Kevin Walker
Kevin Walker
2,354 Points

Overriding Init and properties

One thing I was wondering when i watched the videos was why, when doing the override for the init in SuperEnemy, do we put the code for setting the life property within the override?

class Enemy { var life: Int = 10 let position: Point

init(x: Int, y: Int)
{
    self.position = Point(x: x, y: y)
}

func decreaseHealth(factor: Int){
    life -= factor
}

}

class SuperEnemy: Enemy { let isSuper: Bool = true

override init(x: Int, y: Int) 
{
    super.init(x: x, y: y)
    self.life = 50
}

}

Yigit Yilmaz
Yigit Yilmaz
6,245 Points

While using 'life' in 'Enemy' it is a variable for using decreaseHealth. 'SuperEnemy' subclass already have 'life' variable but must assign new value. It is logic of inheritance. Super Enemies' life must 50 not 10. For this goal, we re-assigned 'life' in override init.

1 Answer

Oliver Duncan
Oliver Duncan
16,642 Points
Oliver Duncan
Oliver Duncan
16,642 Points

Like Yigit says, we override the init method because all instances of SuperEnemy inherit, and are initialized with, a life property with a value of ten. We want the SuperEnemy to have a life of 50, so we override the initializer and give its life a value of 50.

If you're wondering why we don't override the life variable in the beginning of the subclass declaration, I'm not sure. It would be nice if we could just write "override var life = 50," but trying it out results in a compiler error. Probably something to do with what Swift does under the hood.